Maximilian Reichel created WICKET-7055:
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Summary: AjaxEventBehavior onload event unstable
Key: WICKET-7055
URL: https://issues.apache.org/jira/browse/WICKET-7055
Project: Wicket
Issue Type: Bug
Components: wicket-core
Reporter: Maximilian Reichel
As today the AjaxEventBehavior class is not compatible to be used with the
onload event but I could not find this to be documented anywhere.
When using the AjaxEventBehavior class to hook into the onload event, it works
sometimes but it is not stable. This is because AjaxEventBehavior class itself
uses the dom ready event to add the user-defined hooks to the page, but as
clarified [here|https://github.com/jquery/jquery/issues/5075], the jQuery dom
ready event may fires later than the onload event. In this instance the
AjaxEventBehavior adds the user-defined onload hook after the onload event was
already fired and therefore the user-defined hook is never executed.
As a workaround (tested with wicket 6.18.0) I wrote this class which directly
hooks onto the onload event:
{code:java}
import org.apache.wicket.Component;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxEventBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.head.OnLoadHeaderItem;
public abstract class AjaxOnLoadEventBehavior extends
AbstractDefaultAjaxBehavior {
@Override
public void renderHead(final Component component, final IHeaderResponse
response) {
super.renderHead(component, response);
if (component.isEnabledInHierarchy())
{
CharSequence js = getCallbackScript(component);
response.render(OnLoadHeaderItem.forScript(js.toString()));
}
}
@Override
protected void respond(AjaxRequestTarget target) {
onLoad(target);
}
protected abstract void onLoad(final AjaxRequestTarget target);
}
{code}
In my opinion this should be added to the documentation and the
AjaxEventBehavior class should log a warning when used with the onload event.
Maybe wicket could include a class like my AjaxOnLoadEventBehavior.
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